I am experiencing a similar, but slightly different error, since upgrading to WordPress 3. Instead of “Session key invalid or no longer valid” mine states “A session key is required for calling this method”
I’m running WordPress 3.0, and version 3.2.1 of the plugin. PHP 5.2.10
Fatal error: Uncaught exception ‘FB_FacebookRestClientException’ with message ‘A session key is required for calling this method’ in /var/www/wp-content/plugins/fotobook/facebook-platform/facebookapi_php5_restlib.php:3003 Stack trace: #0 /var/www/wp-content/plugins/fotobook/facebook-platform/facebookapi_php5_restlib.php(1608): FB_FacebookRestClient->call_method(‘facebook.photos…’, Array) #1 /var/www/wp-content/plugins/fotobook/fotobook.php(258): FB_FacebookRestClient->photos_getAlbums(112352399784, NULL) #2 /var/www/wp-content/plugins/fotobook/cron.php(12): FacebookAPI->update_albums() #3 {main} thrown in /var/www/wp-content/plugins/fotobook/facebook-platform/facebookapi_php5_restlib.php on line 3003